'I will do my best to do my duty to God and my country': Scouts from Pack 235 saluting during a Memorial Day flag-raising. Photo: UPI

As America celebrates free dom this Independence Day, some 35,000 boys are preparing for a first-hand encounter with it later this month — at a national jamboree that will mark the 100th anniversary of the Boy Scouts. Amid the weekend fireworks, it’s worth a minute to pay tribute to this honorable movement — and to marvel at the monster Scout-fest on tap.

For more than a week, 880 troops will overrun Fort A.P. Hill — a military training site (named for a Confederate commander) near Bowling Green, Va., nearly 100 times the size of Central Park. The site has hosted the event every four years since 1981, but this is the final year; in 2013, jambo moves to a permanent home at the National Scout Reserve in West Virginia.

At Fort A.P. Hill, 8,000 staffers will oversee a veritable Scout city, complete with its own public transit, hospital, postal and phone systems, radio station, daily newspaper, trading posts and food warehouses — not to mention the trails, campsites, exhibits, arena, flag grounds, religious facilities, shooting range and other amenities sufficient to thrill an army of 12- to 17-year-old boys.

Topping the agenda is a centennial parade in Washington, the first Scout-themed march there since the inaugural jamboree 63 years ago. In Virginia, activities will reflect Scout skills and values: physical fitness, America’s heritage, conservation, brotherhood. A Webcast closing show will highlight the anniversary.

The boys will enjoy considerable freedom — and coveted “independence” from parents. Those concepts, individual liberty and parental separation, are key to scouting — because with them come vital assets: self-reliance, leadership, a sense of duty toward others — that is, a personal obligation to act with integrity and treat others considerately.

These ideas underlie America’s greatness in unspoken ways. The Scout Oath requires adherents “to do my best to do my duty to God and my country,” “to help other people at all times,” “to keep physically strong, mentally awake and morally straight.” A Scout, as we all know, is “trustworthy, loyal, helpful, friendly, courteous, kind, obedient, cheerful, thrifty, brave, clean and reverent.”

These are not mere words, but core threads woven through the American fabric. Since gaining independence 234 years ago, America — like a good Scout — has generally sought to follow a similarly noble path, taking up great obligations to its needy, and to the world.

Last year, individual Americans voluntarily donated $227 billion to charity, according to Indiana University’s Center on Philanthropy. Hundreds of billions each year in taxpayer money go for social-service programs, here and abroad. We respond to tsunamis and earthquakes around the globe like no nation in history.

Most notably, our willingness to put our young troops (many, former Scouts) in harm’s way to protect and defend others remains unparalleled; Iraqis and Afghans are the most recent beneficiaries.

The imperative to lend a hand has been a driving force for Scouts since their founding in 1910 — when, legend has it, Chicago newspaperman W.D. Boyce, lost in a London fog, was aided by a British Scout, and inspired to start a movement here. The group’s stated goal back then: “to teach patriotism, courage, self-reliance and kindred values” to America’s boys.

Sure, Scouts have endured their share of scandal and controversy — pedophile horrors and spats over the group’s right to ban gays and atheists and to receive public funds, despite an emphasis on God and religion. As one of the largest movements in the country (with 4 million current Scouts and 110 million since 1910), that’s to be expected. Nor is scouting unique to America, though it may have contributed to our national uniqueness.

At this year’s centennial jamboree, our boys will be, well . . . boys. They’ll learn skills, make friends, earn merit badges, get in trouble — and have fun.

But, rest assured, the experience will reinforce valuable Scout tenets, like self-reliance and liberty — the kind of values that helped drive the colonists to split from their own parent nation, and that have animated the best in America ever since.

As the kids learn and grow,

so, too, will the nation grow stronger.

Adam Brodsky, a one-time Boy Scout, has three sons in the Scouts, including their troop’s senior patrol leader. Two are headed for this month’s National Scout Jamboree. abrodsky@nypost.com